The present disclosure relates to a method for controlling a camera module, and more particularly, to a method for controlling discrete automatic focusing of a camera module using a diffraction device, and a method for correcting a discrete automatic focusing error.
In a related art lens focusing method, focusing is performed by moving a lens. The related art lens focusing method is classified into a variable focus liquid lens driving method using hydraulic pressure, a piezoelectric method using a piezoelectric effect, a voice coil motor (VCM) method using the principle of Lorenz force, a smooth impact drive mechanism (SIDM) actuator method using a field effect transistor, and a Helimorph method depending on a lens driving method.
As cellular phones and digital cameras are miniaturized and become slim, miniaturization and slimness in the size and volume of a camera module are required. Making a slim camera module having a related art driving method for moving a lens such as a stepping motor method, a VCM method, and a piezoelectric method has a limitation.
To resolve a limitation in a method of controlling a focus distance by moving the position of a lens, a method of fixing the position of a lens and controlling the curvature of a reflective type curvature variable diffraction device has been proposed recently. In this method, focusing is performed according to a so-called continuous automatic focusing method of sequentially changing the curvature of a curvature variable diffraction device within a focus variable range.
Since a related art automatic focusing method uses the same focusing method regardless of where a focusing position is located, it is not suitable for a recent apparatus requiring a complicated and fast response.
Therefore, a focusing method that can perform automatic focusing through a faster and simpler operation is required.